High-energy trauma of the mid-face frequently results in bone fracture and a loss of bony fragments within the orbit. It frequently happens, that bony fragments formed upon the fracture cannot be fixed together or are missing and thus, the reconstruction of the orbit is required.
In prior art clinical practice, defects of the orbit, e.g. orbital floor defects are usually treated using metallic, e.g. titanium mesh or nondegradable polymeric implants. The main disadvantage with using nonresorbable implants, however, relates to the necessity of the implant removal from the implantation site, once the healing process is completed. The second operation is traumatic, may lead to secondary infection and increases overall costs of surgical treatment.
The use of a resorbable devices for the reconstruction of the orbit is certainly advantageous, as it avoids second operation. There were several efforts to use resorbable polymers for the treatment of small orbital floor fractures in experimental animals as described by Cutright DE and Hunsuck EE ["The repair of fractures of the orbital floor using biodegradable polylactic acid", Oral Surgery, 33(1), 28(1972)]. In this prior art publication the use of a planar sheet of polylactic acid for the reconstruction of the floor of the orbit is disclosed. The planar sheet is inserted in the orbit, adapted according to the anatomical needs, removed form the orbit and recontoured and finally reinserted into and fixed to the orbit by sutures.
Resorbable devices for treatment of newly created bone voids--a concept which is closely related to Cutright's publication--were disclosed in the U.S. Pat. No. 4,186,448 of BREKKE. In this prior art publication the use of a planar one-piece body of mouldable biodegradable material with randomly shaped interconnected voids therein and having an overall porosity of about 90% is disclosed for the purpose of orbital floor reconstruction.
The main drawbacks of the devices described in these prior art documents relate to their rigidity and limited functionality, in particular to their non-adaptability to the anatomical shape of the orbit. In general therefore, they can only be used for the repair of small defects e.g. in the orbital floor region.